Fuel systems often include a source of pressurized fuel, one or more fuel injectors, and a distribution system for directing the pressurized fuel from the source to the fuel injectors. The fuel injectors are typically associated with an engine and it can be important for proper operation of the engine to monitor and adjust various parameters of the fuel system during operation of the engine. For example, over time, the different components of the fuel system may wear causing efficiency losses and/or gradual deviations from desired operating pressures. If these losses and pressure deviations are left unchecked, the performance of the engine may deteriorate. In addition, if the wear is excessive or damage to the system occurs, external fuel leakage and extreme system pressure drop may be possible.
However, if the efficiency losses and pressure deviations can be monitored, corrective and/or precautionary actions may be timely implemented. One example of monitoring fuel system operation and detecting fuel leakage is described in U.S. Pat. No. 5,708,202 (the '202 patent) issued to Augustin et al. on Jan. 13, 1988. Specifically, the '202 patent discloses a method of recognizing fuel leakage from the fuel injection system of an internal combustion engine. The method includes sensing a pressure of the fuel injection system during non-injection events, and comparing the sensed pressures. If a significant deviation in the sensed pressures occur, then leakage is determined. When determining large leaks between the pump and injectors of large flow systems, the non-injection events correspond with the time between the end of one injection and the start of another injection. When determining leaks between the pump and the injectors in small flow systems, the non-injection events must be created by eliminating at least one fuel delivery and at least one fuel injection step. If no leaks are detected between the pump and the injectors, other portions of the system can be leak tested only during a “driven operation” by comparing the pressures sensed when the injectors and the pump of the system are turned off.
Although the method of the '202 patent may sufficiently detect fuel system leaks, it may be limited and intrusive. In particular, the leak testing described in the '202 patent can only be performed during certain engine operations (e.g., when the engine is driven). This limited applicability may be problematic in some situations where continuous leak detection is critical. In addition, because leak testing within the fuel system of the '202 patent, other than between the pump and the injectors, requires the injectors and the pump to be turned off, engine operation may be undesirably interrupted. Further, the method of the '202 patent provides no way to determine if a low pressure event is due to leakage, periodic intentional pressure relieving, or normal wear, and no way to accommodate normal wear.
The control system of the present disclosure solves one or more of the problems set forth above.